Preheat oven to 350º. Line 13x9-inch baking pan with foil; set aside.
In bowl, combine 1 cup flour and sugar; cut in butter until crumbly. Press on bottom of pan. Bake 15 minutes.
In another bowl, beat Eagle Brand, cocoa, egg, remaining 1/4 cup flour, vanilla and baking powder. Mix in chocolate pieces and nuts. Spread over prepared crust. Bake 20 min. or until set.
Cool. Use foil to lift out of pan. For hearts, cut with heart-shaped cookie cutter or, with knife, cut around waxed paper heart shape. Or cut into bars. Decorate with icing or gels if desired. Store covered.